gh-106560: Fix redundant declarations in Include/ (#112611)

Don't declare PyBool_Type, PyLong_Type and PySys_Audit() twice, but
only once.

Compiler warnings seen by building Python with gcc -Wredundant-decls.

Author: vstinner

Include/boolobject.h

@@ -7,7 +7,7 @@ extern "C" {
 #endif
 
 
-PyAPI_DATA(PyTypeObject) PyBool_Type;
+// PyBool_Type is declared by object.h
 
 #define PyBool_Check(x) Py_IS_TYPE((x), &PyBool_Type)
 

Include/cpython/sysmodule.h

@@ -4,10 +4,6 @@
 
 typedef int(*Py_AuditHookFunction)(const char *, PyObject *, void *);
 
-PyAPI_FUNC(int) PySys_Audit(
-    const char *event,
-    const char *format,
-    ...);
 PyAPI_FUNC(int) PySys_AddAuditHook(Py_AuditHookFunction, void*);
 
 typedef struct {

Include/longobject.h

@@ -7,7 +7,7 @@ extern "C" {
 
 /* Long (arbitrary precision) integer object interface */
 
-PyAPI_DATA(PyTypeObject) PyLong_Type;
+// PyLong_Type is declared by object.h
 
 #define PyLong_Check(op) \
         PyType_FastSubclass(Py_TYPE(op), Py_TPFLAGS_LONG_SUBCLASS)

Misc/NEWS.d/next/C API/2023-12-02-02-08-11.gh-issue-106560.THvuji.rst

@@ -0,0 +1,2 @@
+Fix redundant declarations in the public C API. Declare PyBool_Type,
+PyLong_Type and PySys_Audit() only once. Patch by Victor Stinner.